That is if they first declare that not all opposition to same-sex marriage is homophobic and discriminatory.

As both sides of the debate continue their public campaigns, Cardinal Pell has written a letter in response to a request from gay marriage campaigners for a formal meeting to discuss the issues polarising the community.

The official gay marriage campaign, Australian Marriage Equality, wrote to the Archbishop of Sydney on December 20 to discuss their concerns about a campaign by the Australian Catholic Church against same-sex marriage.

Cardinal Pell surprised gay marriage supporters with a reply on December 22 saying a meeting might be possible. But he wanted a guarantee first that the church's position would not be depicted as hateful.

"It would help me in considering your request for a meeting to receive an assurance that you . . . do not regard opposition to same-sex marriage in itself as a form of prejudice and discrimination, and that you are prepared to say this publicly.

"I am grateful for your request for a meeting to discuss these matters and am open to considering such a meeting," he wrote.

"I can offer you no assistance on the second reason you have asked for this meeting (to prevent Catholic clergy from actively campaigning against same-sex marriage), and on most of the substantive matters I expect we will have to agree to disagree.

"But it is always good to talk whenever this might be helpful."

Cardinal Pell said he was prepared to meet a same-sex couple who have been civilly married in another jurisdiction if a Catholic married couple could also be present "so that they can explain their concerns about same-sex marriage and what it might mean for the sort of commitment they have made".

In his letter in reply, Peter Furness, acting national convenor of the gay marriage campaign, said he would be happy for Cardinal Pell to be accompanied by a Catholic married couple.

A spokesman for the gay marriage campaign, Rodney Croome, told The Australian he was willing to concede that the Catholic Church did not intend to discriminate, meeting part of Cardinal Pell's demand for a meeting.